Table 11.
Reliability and unidimensionality of the full scale, short form, and subscales
| |
Full scale |
Short form |
1-11 |
12-19 |
20-39 |
40-49 |
50-68 |
|---|---|---|---|---|---|---|---|
| (68 items) | (34 items) | (Pain) | (Stiffness) | (Difficulty) | (Limitation) | (Social issues) | |
|
Person Reliability |
.96 |
.95 |
.89 |
.89 |
.94 |
.78 |
.84 |
|
Cronbach’s Alpha |
.98 |
.97 |
.93 |
.95 |
.97 |
.87 |
.94 |
|
Unidimensionality Criteria (Ratio of the raw variance explained by measures: Unexplained variance in 1st contrast ≥ 3) |
56.8/10.6= |
60.2/15.8= |
66.7/22.1= |
67.5/34.7= |
72.7/15.5= |
63.4/19.2= |
53.6/18.1= |
| 5.4 |
3.8 |
3.0 |
1.941 |
4.69 |
3.32 |
2.963 |
|
| Yes | Yes | Yes | No | Yes | Yes | No |
1 Further inspection of the data revealed that the two-factor solution was associated with the severity of the items, where the two factors were actually low and high severity stiffness, i.e. opposite poles of the same factor. Therefore, the scale is useful as a measure of stiffness. 2 These were the results after removing item 41 (ASSISTO).
3 Approximately unidimensional.